Method for altering plant flowering and sexual reproduction

ABSTRACT

A method for altering plant flowering and/or plant sexual reproduction involving application of an allophanimidate such as methyl 4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate or methyl 4-(p-chlorophenyl)-N-methylthiolcarbonylallophanimidate. A preferred use of the invention is to prevent corn inbreeding by applying the allophanimidate to the plant shortly before or at tassel emergence.

United States Patent Lin Aug. 26, 1975 [54] METHOD FOR ALTERING PLANT[56] References Cited FLOWERING AND SEXUAL UNITED STATES PATENTSREPRODUCTION 3,457,063 7/1969 Neighbors 71/111 5 Inventor; Kang Lin,Newark, DEL 3,664,823 5/l972 Loux 71/1 ll [73] Assignee: E. l. Du Pontde Nemours and Primary Examiner james 0 Thomas, In

Company, Wilmington, Del.

[22] Filed: Jan. 30, 1973 [57] ABSTRACT 2 A 1 N ;323 059 A method foraltering plant flowering and/or plant sexual reproduction involvingapplication of an allophanimidate such as methyl 4-(p-chlorophenyl)-N-[52 us. (:1. 71/100; 47/141, 71/101, methoxycarbonylauophanimidate ormethyl 7l/l06; 7l/l05; 7111] l; 260/455 A; 260/471chlorophenyl)-N-methylthiolcarbonylallophanimidate. C A preferred use ofthe invention is to prevent corn in- Int. breeding the anophanimidate othe plant [58] Field of Search 71/100, 11 1, 1013/1112)? shortly beforeor at tassel emergenw 16 Claims, No Drawings 1 METHOD FOR ALTERING PLANTFLOWERING AND SEXUAL REPRODUCTION BACKGROUND OF THE INVENTION Theallophanimidates of this invention and their use as herbicides aredisclosed and claimed in copending US. application Ser. No. 325,357,filed Jan. 22, I973. by Julius .I. Fuchs and Kang Lin, which isacontinuation-in-part of copending US. Patent Application Ser. No.l8l,20l, filed Sept. 16, 1971.

It has now been discovered that the compounds are useful as plantregulants in that they alter plant flowering and/or plant sexualreproduction.

SUMMARY OF THE INVENTION This invention is a method of altering plantflowering and/or plant sexual reproduction which comprises applying anallophanimidate to the plant in an amount which is effective to alterflowering and/or sexual re production of the plant without causingsubstantial fo liar burn, chlorosis or necrosis, the allophanimidatebeing a compound of either of the following formulas:

Formula I R, X, X,

N cN=c N c x,R, l l 3 6 Formula II RI X\ wherein X,, X and X are oxygenor sulfur;

R, is hydrogen or alkyl of I through 4 carbon atoms;

R is alkyl of I through 6 carbon atoms, cycloalkyl of 3 through 8 carbonatoms. cycloalkylalkyl of 4 through 7 carbon atoms, alkenyl of 3 through4 carbon atoms, alkynyl of 3 through 4 carbon atoms, benzyl, or

&

where i Y is hydrogen. halogen, alkyl of 1 through 4 carbon atoms.nitro. alkoxy of I through 4 carbon atoms, alkylthio of I through 4carbon atoms. cyano, or trifluoromethyl; and Z is hydrogen, halogen,methyl, ethyl, nitro, alkoxy of I through 4 carbon atoms, or alkylthioof I through 4 carbon atoms; Q is hydrogen, halogen, or methyl; R is SRor OR where R is alkyl of 1 through 6 carbon atoms, cycloalkyl ol' 3through 8 carbon atoms, alkenyl of 3 through 4 2 carbon atoms, alkynylof 3 through 4 carbon atoms, benzyl or phenyl; and R is alkyl of Ithrough l2 carbon atoms substituted with 03 chlorine atoms or O-lmethoxy group, alkenyl of 3 through 4 carbon atoms, cycloalkyl of 5through 8 carbon atoms, benzyl, or

Qt Z

where Y and Z are as previously defined;

R is hydrogen or alkyl I through 3 carbon atoms. Preferred withinFormula I because of ease of synthesis, higher activity and lowphytotoxicity are those compounds where R, is hydrogen; R is alkyl of 1through 6 carbon atoms, alkenyl of 3 through 4 carbon atoms, or

where Y, Z and Q are as previously defined;

R is alkyl of I through 6 carbon atoms or allyl;

R is alkyl of I through 4 carbon atoms;

R, is hydrogen or methyl;

X and X are oxygen; and

X is oxygen or sulfur. t

Particularly preferred highly active compounds are those compounds whereR, is hydrogen;

R2 IS where molecule are possible when R is hydrogen;

For this reason. all compounds when R is hydrogen are namedallophanimidates according to form (A). Compounds of Form (C) are alsonamed as allophanimidates, while compounds of Form (D) are named ascarbamates.

equivalent oftriethylamine (equation 2). The methylene chloride solutionis washed with water. dried. and i stripped to afford the carbamates andthe thioallophanimidates of this invention in good purity. As can beseen from the discussion of nomenclature above,

A preferred embodiment of this invention is a method of preventinginbreeding of corn which comprises applying an allophanimidate ofFormula I or Formula ll to the corn before or at tassel emergence in anamount sufficient to prevent self-fertilization but insufficient tocause substantial foliar burn. cholorsis or necrosts.

carbamates result when R is alkyl and thioallophanimidates result when Ris hydrogen. The reaction product can be further purified by dissolvingit in dimethylformamide and precipitating it by adding water or byrecrystallization from hexane.

Thioallophanimidates of Form (C) can be obtained by reacting the2-thiopseudourea first with a chloroformate and then an isocyanate as inequations 3 and 4.

R. 0 SR, (31 it o Cl-C-OR tC H, LN ll RN NH Lil? RN NC0R SR. 0 s R.

ll (4) RTNCO R-NC N-c-oR, -e R.-NCNC=NCOR,

H II H t It DETAILED DESCRIPTION OF THE INVENTION where The compounds ofthe invention can be made by the R R R and R, are as defined forequations l and process illustrated by the following equations: (2).

sR. a7 slt. ll l R=-NCO /NCN=CNR.,

H HN NHR H R-,\ o SR. (n) R,\ C) SR. 0 ll (CsH ms ll (2} N-(N=C-N-R.+c|-C-o|t. 5 N C-N=c-|lv-C oR,

H H H u where R R and R are as previously defined and R is R or R Inequation (I) the Z-thiopsaudourea is liberated from its correspondingchloride or sulfate with one mole of base and reacted with an isocyanatein a solvent. e.g.. water, aqueous methanol or aqueous acetone. at about0C. The reaction mass is warmed to room temperature and the solventremoved by evaporation The intermediate thioallophanimidate is collectedby filtration and dried (This reaction is essentially the same method asdescribed in Organic Synthesis, 42. 87, for the preparation of methyl4-phenyl-3- thioallophanimidate).

The intermediate is reacted with one equivalent of a chloroformate inmethylene chloride containing one In Equation (3) the 2-thiopseudoureasulfate and a chloroformate in water are cooled to about 0C. and

two equivalents of base are added gradually. The reaction mixture isallowed to come to room temperature and then extracted with methylenechloride. The methylene extract is dried and evaporated to afford theintermediate alkyl N-(l-alkylamino-lmethylthiomethylene)carbamate oralkyl N-( l-aminolmethylthiomethylene)carbamate in excellent purity. Inequation (4) the intermediate is dissolved in methylene chloride and oneequivalent of isocyanate is added. The mixture is stirred for severalhours, and then evaporated to produce the thioallophanimidates inexcellent yield and purity. The product can be further purified usingthe techniques set forth above.

Alkoxycarbonylthioallophanimidates with 2 substitunight and washed oncewith water. After drying and cats in the 4-position can be prepared bystarting with evaporation of the solvent on a rotary evaporator, therethe product of reaction (3) and reacting it with a caris obtained 3.8parts methyl 4-tert-butyl-N- bamoyl chloride in the presence oftriethylamine as il- .methylthiolcarbonyl-l-thioallophanimidate meltingat lustrated by reaction (5). 5 l02l05C.

R, (I) fill, ti) R, o SR, g)

l ((LH ),N NCCI+HNC=NCOCH;. \N-CNC=NC-OCH;,

l l n R2 u In reaction (5) the reactants are heated for l-3 hoursEXAMPLE 2 in the presence of triethylamine in a solvent such as benzeneor toluene. After completion of the reaction,MethyhmterbButyhN-methoxycarbony'-lhthloalky the solvent is evaporated.the residue extracted with phammdate water to dissolve water-solublesubstances. and the res- To 5.67 parts of methyl4-tert-butyl-l-thioalloidue recrystallized from benzene. phanimidate,prepared as in Example I, and 4 parts of The corresponding disubstitutedcarbamates are simtriethylamine in parts methylene chloride at 0C. isilarly prepared from Z-thiopseudourea, carbamoyl added dropwise 2.8parts methyl chloroformate in 5 chloride and triethylamine asillustrated by reactions parts methylene chloride. The solution isstirred overa night and washed once with water. After drying and Thefollowing examples are offered to illustrate the evaporation ofthesolvent on a rotary evaporator, there processes described above. Allparts are parts by is obtained an oil which turned crystalline. Aftertrituweight unless otherwise indicated. ration with hexane it affords1.9 parts methyl 4-tertbutyl-Nmethoxycarbonyl-l-thioallophanimidatemelt- EXAMPLE 1 ing at 8790C.

Methyl EXAMPLE 3 4-tertbutyl-N-methylthiolcarbonyll Methylthoianophammldme 4-isopropyl-N-methoxycarbonyll -thioallophanimidate To139 parts 2-methyl-2-thiopseudourea sulfate in To 69.5 partsZ-methyl-2-thiopseudourea sulfate and 1000 parts 50% aqueous methanol at0C. is added 47 parts of methyl chloroformate in I000 parts waterdropwise 88 parts 50% sodium hydroxide, followed by at 0C is addeddropwise 56.9 parts of potassium hy- 90 parts tert-butylisocyanate in200 parts tetrahydrodroxide in 200 parts of water. The reaction mixtureis fur-an. The solution is then stripped of most of the stirred at roomtemperature for 3 hours and then exmethanol and tetrahydrofuran on arotary evaporator tracted with methylene chloride. The methylene chloandfilterd to yield after drying parts methyl 4-tertride extract is driedand the solvent evaporated on a robutyl-l-thioallophanimidate melting atl02104C. tary evaporator to give 45 parts of methyl N-( l-amino- To 5.67parts of the above compound and 4 parts tri- Ml-methylthiomethylene)carbamate melting at ethylamine in 50 pansmethylene chloride at 0C. is 7277C. added dropwise 3.3 parts methylchlorothiolformate in Seventy-four parts of the above compound and 47 5parts methylene chloride. The solution is stirred overparts of isopropylisocyanate in 300 parts methylene EXAMPLE 4 Methyl4-methyl-N-methylthiolcarbonyl l -thioallophanimi date To 69.5 parts2-methyl-2-thiopseudourea sulfate ahd llO parts methylchlorothiolformate in 500 ml. of water is added dropwise at (]5C. 120parts 50% sodium hydroxide. The reaction mixture is stirred at -5C. forl hour and then at room temperature for 2 hours. The solution isextracted with methylene chloride. The methylene chloride extract isthen dried and the solvent evaporated on a rotary evaporator to give 47parts of methyl N-( l-aminol methylthiomethylene )thiolcarbamate meltingat 7576C.

To 8.2 parts of the above compound in 75 parts methylene chloride isadded 3.1 parts methyl isocyanate. The reaction mixture is stirred atroom temperature for 3 hours, and then stripped of solvent on a rotaryevaporator to give parts methyl 4-methyl-N-methylthiolcarbonyl-l-thioallophanimidate melting at l l5-l 17C.

EXAMPLE 5 Methyl 4-( p-chlorophenyl )-N-methoxycarbonyll-thioallophanimidate EXAMPLE 6 Methyl 4-sec-butyl-N-methoxycarbonyll-thioallophanimidate To 7.2 parts methylN-(l-amino-l-methylthiomethylene)carbamate, prepared as in Example 3, in50 parts methylene chloride is added 5.5 parts secbutylisocyanate. Thereaction mixture is stirred overnight and the solvent is evaporated on arotary evaporator to give 12 parts methyl 4-sec-butyl-N-methoxycarbonyl-l-thioallophanimidate melting at l02- l 04C.

EXAMPLE7 Methyl 4-isopropyl-N-ethoxycarbonyll -thioallophanimidate Tol38 parts 2-methyl-2-thiopseudourea in 500 parts water at U-l0C. isadded 80 parts 50% sodium hyt 8 droxide. One liter of cold acetone isadded followed by dropwise addition of parts isopropyl isocyanate. Themixture is allowed to stay at room temperature for 2 hours andevapbratedon a rotary evaporator. Thesolid is collected" and dried to give partsmethyl 4- .isopropyl-l-thioallophanimidate melting at 8l'-85C.

To 8.8 parts of the above compound and 6.0 parts ethyl chloroformate at(1C. is added dropwise 8.4 parts triethylamine. The reaction is stirredat room temperature for 3 hours. Water is added and stirred for a while.The methylene chloride layer is dried and evaporated on a rotaryevaporator to give after hexane trituration, 102 parts methyl4'isopropy1-N-ethoxycarbonyl-l-thioallophanimidate melting at MP-92C.

EXAMPLE 8 I Methyl 4-propyl-N methoxycarbonyll -thioallophanimida'te To7.4 parts of methyl N-( l-aminp-l -njlethylthiomeithylene)carbamateprepared in Exampl 3 inSO parts of methylene chlorideis added 4.7 partsof propyl isocyanate. The reaction mixture is stirred overnight and thesolvent is stripped on a rotary evaporator to give a solid whichdissolved in be nzene and precipitated by adding hexane. The solid iscollected and dried to give 10 parts of methyl 4-propyl-N-methoxycarbonyl l -thioallophanimidate melting at 68-69C.

EXAMPLE9 4 4-( p-chlorophenyl )-N-methoxycarbonylallophanimidate To l3parts of methyl N-( l-amino-l-methoxymethylene)carbamate, m.p. 36-39.5,prepared similar to the procedure in Example 3 for methyl N-(l-amino-lmethylthiomethylene)carbamate in M0 parts of methylene chlorideis added 15 parts of p-chlorophenyl isocyanate. The reaction mixture isstirred overnight and the solution filtered to give 10 parts of methyl44pchlorophenyl)-Nmethoxycarbonylallophanimidate melting at l70 dec.

EXAMPLE l0 I Methyl. r y 4-( p-chlorophenyl)-N-methylthiolcarbonylallophanimidate i To 9 parts of methyl N-(l-aminol Pseudothiourcu ur Psueod urea lsocyanatc or lsothioeyanuteContinued Fnrmatefl'hiolflwrmatc or Dithinfurmutc AllophunimidutesZ-methylpse udourcu p-hromuphcnyl isocyunutc p-hromophcnyl isocyunatepmclhylphcnyl isocyunulc p-methylphenyl isocyanate p-methoxyphenylisoeyanate p-mcthoxyphcnyl isocyunate p-fluorophenyl isocyanatep-fluomphenyl ismethyl chlorofumwte methyl chlorothiolformale methylchlurofurmutc methyl chlorothiolfol-mate methyl chloroform-ate methylchluruthrmate methyl chlorofurmate methyl ehlomthiolmethyl4-(p-hromophenyl l-N-methoxycurhonylallophanimidate methyl4-1p-hmmophcnyll-N-methylthinlcurhonylallophanimidute methyl 4-(p-methylphenyl l-N-mcthoxy- ,curb0nylalluphanimidate methyl4-(p-methylphenyl l-N-methylthiolcarhonylallophanimiclale methyl4-(p-methoxyphenyl )-N-methoxycarhonylallophanimidate methyl4-(p-methoxyphenylJ-N-melhylthiolcarbonylallophunimidate methyl 4-(p-fluorophenyl J-N-methoxy carbonylallophanimidate cyanate formatecarbonylallophanimidute Z-methylpseudourea 2.4-(lichlor0phcnyl methylchlorofomtute methyl 4-( 2,4-dichlorophenyl)-N-methoxyisocyanatecarbonylallophanimidate Z-methylpseudourca 2.4-dichlorophenyl methylchlorothiolmethyl 4-(2.4-diehlorophenyl-N-methylisocyanatc furmatethiolcarbonylallophanimidale Z-methylpseudourea m-hutylphenylm-butylphenyl methyl 4-(m-butylphenyl)-N-(m-butylisocyzmutcchloroformate phcnoxycarbonyl )-all0phanimidale Similarly, the followingcarbamates can be prepared.

Pseudothioureu, lsocyanate or Formatc. Thiolformate or Pseudourealsothiocyunate or Dithioformatc Carbamatesl,2-dimethyI-Z-thiopscudocyclopentyl isomethyl chlorofnrrnate methyl N-(l-cyclopentylcarbamylimino-lurea cyan-ate methylthiomethyl)-N-methylcarbamate |,Z-dimethyl-Z-thiopseudocyelohexyl isomethylchloroformate methyl N-( l-eyclohexylcarbarnyliminolurea V cyunatcmethylthiomethyl )-N-methylcarbamate Z-mcthyl-l-propyl-Z- cyclopentylisomethyl chloroformate methyl N-(l-cyclopcntylcarbamylimino-lthinpseudoureu cyunate methylthiomcthyll-N-propylcarbumute LZ-dimcthyl p-chlorophcnyl methyl chloroformatemethyl N-( l-p-chlorophenylcarbamylpseudoureu isocyunatc iminol-methoxymethyl )-N-methylcarhumute EXAMPLE ll they will contain theseingredients in the following Methyl 4.4-dimethyl-N-methoxycarbonyll-thioapproximate proportions:

allophanimidate Percent by Weight To a solution of 14.8 parts ofN-(l-ammo-lmethylthiomethylene)carbamate and 10.] parts of l 1 clientDiluent s) Surfactants) trlethylamme tn 100 parts of benzene 18 added Hparts dimethylcarbamoyl chloride and the reaction g q l USpCl'lSl0l'lS\rmxture refluxed for two hours. The reaction mixture EmulsionsysolmionsIS then sub ected to vacuum and the solvent evapo- (including Emulsi- 50 5 fiable Concentrates) 5-50 40-9 rated. The residue 18 then tnturatedw th 200 parts of Aqueous Suspensions H0 4044 water at room temperature.the remaining SOlldS arc Dusts 1-25 70-99 0-5 then recrystallized frombenzene to give pure methyl g gg'gfiiggf 4.4-dimethyl-N-methoxycarbonyll -thioallophani- Compositions 90-99 midate. in FZ S Z ZE S S i P g' 'ithe follow' Lower or higher levels of active ingredient can, of

: th 4 1 ii e i f l fi course. be present depending on the intended useand e y y g i gz 0 the physical properties of the compound. Higherratios meth [4 th th Garb l l of surfactant to active ingredient aresometimes dey me i' H F oxy ony sirable. and are achieved byincorporation into the ma 0p ate formulation or by tank mixing. Lowerconcentrations F l i fth Compounds 5 of active ingredient can aid inaccurate application at the very low rates reached for this invention.Spray- Formulations of the compounds of Formulas l and abl a d dustformulations are preferred.

U m use this "'lvemlon can P p fl- Typical solid diluents are describedin Watkins, ventional ways. They include dusts. granules. Pellets, etal.. Handbook of Insecticide Dust Diluents and Solutions. P N.cmulslons. fitl e Powders. Carriers". 2nd. Edn., Dorland Books,Caldwell, NJ.

emulsifiable concentrates and the like. Many of these may be applieddirectly. Sprayable formulations can be extended in suitable media andused at spray volumes of from a few pints to several hundred gallons peracre. High strength compositions are primarily used as intermediates forfurther formulation. The formulations. broadly, contain about I% to 99%by weight of active ingredient(s) and at least one of a) about ().I% to20% surfactant(s) and b) about 5% to 99% solid or liquid diluentlsl.More specifically.

The more absorptive diluents are preferred for wettable powders and thedenser ones for dusts. Typical liquid diluents and solvents aredescribed in Marsden, Solvents Guide, second edition, lnterscience, NewYork, 1950. Solubility under 0.5 is preferred for suspensionconcentrates; solution concentrates are preferably stable against phaseseparation at 0C. McCutcheons Detergents and Emulsifiers Annual, AlluredPubl. Corp., Ridgewood. New Jersey. as well as Sisely and Wood,

13 Ridgewood. New Jersey. as well as Sisely and Wood. Encyclopedia ofSurface Active Agents". Chemical Publ. Co.. lnc.. New York. 1964. listsurfactants and recommended uses. All formulations can contain minoramounts of additives to reduce foam. caking. corrosion. microbiologicalgrowth. etc.

The methods of making such compositions are well known. Solutions areprepared by simply mixing the ingredients. Fine solid compositions aremade by blending and. usually. grinding as in a hammer or fluid energymill. Suspensions are prepared by wet milling (see. for example.Littler, U.S. Pat. No. 3.060.084). Granules and pellets may be made byspraying the active material upon preformed granular carriers or byagglomeration techniques. See J. E. Browning. "Agglomeration". ChemicalEngineering. Dec. 4. 1967. pp. 147ff. and Perry's Chemical Engineer'sHandbook". 4th. Edn., McGraw-Hill. N.Y., 1963, pp. 8-59ff.

For further information regarding the art of formulation, see forexample:

H. M. Loux. U.S. Pat. No. 3,235,361. Feb. 15.1966.

Col. 6. Line 16 through Col. 7. Line 19 and Examples through 41.

Rv W. Luckenbaugh. U.S. Pat. No. 3,309,192. Mar. 14. 1967. Col. 5 Line43 through Col. 7 Line 62 and Ex. 8. l2. 15. 39.41. 52, 53.58.132.138-140. 162-164. 166. 167. 169-182.

H. Gysin and E. Knusli. U.S. Pat. No. 2.891.855. June 23. 1959. Col. 3Line 66 through Col. 5 Line 17 and Examples l-4.

G. C. Klingman. Weed Control as a Science", John Wiley and Sons. Inc..New York. 1961 pp. 81-96.

J. D. Fryer and S. A. Evans, Weed Control Handbook". fifth editionBlackwell Scientific Publications. Oxford. 1968. pp. 101-103.

Typical formulations are shown in the following examples. Allpercentages are by weight.

Thoroughly blend the ingredients then pass through an air mill toproduce an average particle size under microns. Reblend and sift througha U.S.S. No. 50 sieve (0.3 mm opening) before packaging.

All compounds of the invention may be formulated in the same manner.

EXAMPLE 13 High Strength Concentrate Percent methyl 4(p-Chlorophcn) lLN-methoxyearbonyl 98.5

allophanimidate silica aerogel 0.5

synthetic amorphous fine lllClt 1 1| Blend and grind the ingredients ina hammer mill to produce a high strength concentrate essentially allpassing a U.S.S. No. 50 sieve (0.3 mm openingsl. This material may thenbe formulated in a variety of ways.

EXAM PLE 14 Dust Percent high strength concentrate. Example 13 25.4pyrophyllite. powdered 74.6

Thoroughly blend the ingredients and package for use.

EXAMPLE l5 Aqueous Suspension Percent methyl 4-4p-chlorophcnyll-N-mcthoxycarhonylallophanimidate hydrated attapulgite 3crude calcium ligninsulfonate 10 sodium dihydrogen phosphate 0.5 water6L5 Grind the ingredients together in a sand mill until the solidparticles have been reduced to diameters under 10 microns.

Grind the ingredients together in a sand mill until the solid particleshave been reduced to under about 5 microns. The resulting thicksuspension may be applied directly. but preferably after being extendedwith oils or emulsified in water.

Use of the Invention This invention can be used to facilitate theproduction of many hybrid crops. For example. in the production ofhybrid corn, it can be used to prevent inbreeding. An allophanimidateofformula l or formula 11 is applied to the corn plant. to be used asthe female parent. preferably in a spray or dust formulation. shortlybefore or at tassel emergence. This treatment substantially preventspollen shed and may also destroy pollen viability. thus making itunnecessary to detassel. The invention can be used in a similar mannerto prevent inbreeding of other crop plants. e.g. wheat. rice. andsoybeans. by treating the plants at or near flowering with anallophanimidate of formula 1 or formula 11.

The invention can also be used to alter fruit set pattern of variouscrops such as cotton. tomatoes. citrus fruit. peaches. and apples. inthese crops it is often desirable to prevent late fruit set ordevelopment in order to facilitate mechanical harvesting. and/oreliminate the necessity of thinning. This can be accomplished byapplying an allophanimidate of formula 1 or formula 11 to the plantafter the desired amount of fruit set has taken place.

Similarly, the invention can be used to eliminate fruit set altogetheron certain types of ornamentals. e.g. locust. and mimosa trees. wherethe fruit may be considcred undesirable.

The invention can be used to prevent seed development in hay crops suchas alfalfa. This is considered dcsirable because the energy that theplant would otherwise use to develop seeds can be used to increaseforage development. Here again. the time to treat the plant is at ornear flowering.

Another use for the invention is to prevent asparagus seed development.Asparagus plants are male or female. Female plants are about lessproductive than male plants, because of the energy utilized in seeddevelopment. By spraying the male plants at or just be fore floweringwith a formulation of an allophanimidate of formula I or formula II.fertilization and seed development can be substantially reduced orprevented, thus increasing yield of the female plants. Prevention ofasparagus seed development is also desirable because otherwise the seedsare dropped. germinate, and the seedlings become a weed problem for themature plants.

Presently in new strawberry plantings, the flowers are pinched offduring the first year in order to prevent fruit set. Fruit hindersdevelopment of the strawberry plant bed. By use of this invention, i.e..by applying an allophanimidate of formula I or formula II to the plantsat or near flowering, the need for hand-pinching the flower buds can beeliminated.

Another use of the invention is to prevent fruit set or seed developmentin ceretain crops which are not harvested for fruit or seed. Forexample. by applying one of the allophanimidates to potato plants at ornear flowering, fruit and seed development which interfere with tuberdevelopment. can be prevented.

Still another use for the invention is to control pollen developmentand/or release in certain noxious weeds. e.g. ragweed.

In this invention the allophanimidates of formulas l and II are appliedto the plant in an amount which is sufficient to produce the desiredchange in flowering and/or sexual reproduction, but which isinsufficient to cause substantial foliar burn, chlorosis, or necrosis.The allophanimidates vary in degree of phytotoxicity, and thephytotoxicity ofa given allophanimidate varies with the plant species.Thus. it is not possible to state a range of application rates whichwill be applicable for all allophanimidates and all plant species. Ingeneral rates in the range of about 0.l to l0 kg./ha. will be used. Thepermissible rates for any combination of allophanimidates and plantspecies can be readily established empirically.

The capability of two allophanimidates of formulas l and II to affectflowering and sexual reproduction of plants is shown in the followinggreenhouse tests:

A. Foliar sprays of methyl 4-(p-chl0rophenyl)-N-methoxycarbonylallophanimidate and methyl 4-(pchloropheny])-N-methylthiol-carbonylallophanimidate on Tenderette bushsnap beans in the bud stage prevented fruit set 3 weeks with littleeffect on vegetative growth. Plants were about 24 days old and 25 to cmtall when sprayed. Data from these greenhouse tests are summarizedbelow:

(I 7 no effect. ll! maximum tuspuns "AHJYHLLL wt 4 replications B. Agwayl5l=S hybrid field corn was grown in 8 inch pots to the stage wheretassels were barely visible deep in some whorls. Foliar sprays of eachof methyl 4-(p-chlorophenyl)-N- methoxycarbonylallophanimidate andmethyl 4-(pchlorophenyl)-N-methylthiolcarbonylallophanimidate at both4.5 kg/ha and 1.1 kg/ha were then applied. Pollen shed was inhibitedwhen plants were observed 1 1 days later.

l. A method for preventing pollen shed in crop plants comprisingapplying an allophanimidate to the plant in an amount which is effectiveto prevent pollen shed 5 without causing substantial foliar burn.chlorosis. or necrosis, the allophanimidate being a compound of eitherof the following formulas:

Y is hydrogen, halogen, or methyl; and Z is halogen;

is methyl or ethyl;

is methyl or ethyl;

is hydrogen;

and X are oxygen; and

is oxygen or sulfur.

2. Method of claim 1 where the crop is a cereal grain crop.

3. Method of claim 2 where the allophanimidate is methyl4-(p-chlorophenyl)-N- methoxycarbonylallophanimidate.

4. Method of claim 2 where the allophanimidate is methyl4-(p-chlorophenyl)N- methylthiolcarbonylallophanimidate.

5. Method of claim 2 where the crop is corn.

6. Method of claim 5 where the allophanimidate ismethyl-44p-chlorophenyl)-N- methoxycarbonylallophanimidatc.

7. Method of claim 5 where the allophanimidate is methyl4-(p-chlorophenyl)-N- mothylthiolcarbonylallophanimidate.

8. Method of claim 2 where the crop is rice.

9. Method of claim 8 where the allophanimidate is methyl4-(p-chlorophcnyl)-N- methoxycarbonylallophanimidate.

l0. Method of claim 8 where the allophanimidate is methyl4-(p-chlorophenyl)-N- methylthiolcarbo nylallophanimidate.

1]. Method of claim 2 where the crop is wheat.

12. Method of claim ll where the allophanimidate is methyl 4-(p-chlorophenyl )-N methoxycarbonylallophanimidute.

13. Method of claim ll where the allophanimidate is methyl4-(p-chlorophenyl)-N- methylthiocarbonylallophanimidate.

14. Method for preventing inbreeding of corn to facilitate theproduction of hybrid seed which comprises applying an allophanimidate tothe corn before or at tassel emergence in an amount sufficient toprevent self-fertilization but insufficient to cause substantial foliarburn. chlorosis, or necrosis, the allophanimidate being a compound ofeither of the following formulas:

wherein [6. Method of claim [4 where the allophanimidate is methyl4-(p-chlorophenyH-N- methylthiolcarbonylallophanimidate.

1. A METHOD FOR PREVENTING POLLEN SHED IN CROP PLANTS COMPRISINGAPPLYING AN ALLOPHANIMIDATE TO THE PLANT IN AN AMOUNT WHICH IS EFFECTIVETO PREVENT POLLEN SHED WITHOUT CAUSING SUBSTANTIAL FOLIAR BURN,CHLORSIS, OR NECROSIS, THE ALLOPHANIMIDATE BEING A COMPOUND OF EITHER OFTHE FOLLOWING FORMULAS:
 2. Method of claim 1 where the crop is a cerealgrain crop.
 3. Method of claim 2 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate.
 4. Method of claim2 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methylthiolcarbonylallophanimidate.
 5. Method ofclaim 2 where the crop is corn.
 6. Method of claim 5 where theallophanimidate ismethyl-4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate.
 7. Method ofclaim 5 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methylthiolcarbonylallophanimidate.
 8. Method ofclaim 2 where the crop is rice.
 9. Method of claim 8 where theallophanimidate is methyl4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate.
 10. Method of claim8 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methylthiolcarbonylallophanimidate.
 11. Method ofclaim 2 where the crop is wheat.
 12. Method of claim 11 where theallophanimidate is methyl4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate.
 13. Method of claim11 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methylthiocarbonylallophanimidate.
 14. Method forpreventing inbreeding of corn to facilitate the production of hybridseed which comprises applying an allophanimidate to the corn before orat tassel emergence in an amount sufficient to preventself-fertilization but insufficient to cause substantial foliar burn,chlorosis, or necrosis, the allophanimidate being a compound of eitherof the following formulas:
 15. Method of claim 14 where theallophanimidate is methyl4-(p-chlorophenyl)-N-methoxycarbonylallophanimidate.
 16. Method of claim14 where the allophanimidate is methyl4-(p-chlorophenyl)-N-methylthiolcarbonylallophanimidate.